This invention relates to a process for preparing 2-aminoethyl methacrylate salts of high purity by the reaction of 2-isopropenyl-2-oxazoline with an acid.
Previously, these compounds have been prepared by reacting ethanolamine with a lower alkyl ester of methacrylic acid or with methacryloyl chloride; by reacting ethylenimine (aziridine) with methacrylic acid, as per U.S. Pat. No. 3,336,358; or by acid hydrolysis of an acryloxyalkylketimine, as per U.S. Pat. No. 3,037,969. Such prior art processes were plagued by low yield and/or a production of an impure and highly colored reaction product.
Sheetz and Steiner (U.S. Pat. No. 3,505,297--column 5, lines 45-57) teach that 2-alkenyl-2-oxazolines can be hydrolyzed under "moderate conditions" with either acid or base hydrolysis. Acid hydrolysis is said to result in the formation of 2-aminoethyl acrylates or methacrylates from the 2-vinyl- or 2-isopropenyl-2-oxazoline, respectively. No further reaction conditions were given but they must have been something less rigorous than the acid hydrolysis condition set forth by Wehrmeister in U.S. Pat. No. 3,466,308. Wehrmeister teaches that the 2-alkenyl-2-oxazolines are hydrolyzed to alkenoic acids by refluxing the oxazoline reactants in water in the presence of an acid catalyst. The acid hydrolysis of other oxazolines is taught by Frump in Chemical Reviews, 71, 483-505 (1971) at page 494.